1. Field of the Invention
The invention relates to a metal-film forming apparatus and a metal-film forming method. More particularly, the invention relates to a metal-film forming apparatus and a metal-film forming method that are capable suitably forming a metal film on a surface of a conductor pattern layer formed on a resin substrate.
2. Description of Related Art
Conventionally, when manufacturing an electronic circuit substrate or the like, a metal film is formed on a surface of a substrate in order to form a metal circuit pattern. As film forming technology of such a metal film, technology that forms a metal film by a plating process such as a non-electrolytic plating process, or film forming technology that forms a metal film by a PVD method such as sputtering, on a surface of a semiconductor substrate of Si or the like, for example, have been proposed.
However, when a plating process such as a non-electrolytic plating process is performed, rinsing after the plating process is necessary, and the resultant waste water must then be disposed of. Also, when a film is formed on a substrate surface by a PVD method such as sputtering, internal stress is generated in the metal-film coating, so there is a limit as to just how thick the film can be. In particular, with sputtering, the film is only able to be formed in a high vacuum.
In view of this, International Publication No. WO 2013/125643, for example, proposes a metal-film forming apparatus that includes a positive electrode, a solid electrolyte membrane arranged between an anode and a metal substrate that serves as a cathode, and a power supply portion that applies a voltage between the anode and the cathode (i.e., the metal substrate).
With this film forming apparatus, metal ions are deposited on a surface of the metal substrate, such that a metal film is able to be formed on the metal substrate, by making the solid electrolyte membrane containing metal ions contact the surface of the metal substrate, and applying a voltage between the anode and the cathode (i.e., the metal substrate) with the power supply portion.
When the film forming apparatus described in International Publication No. WO 2013/125643 is used, it is easy to electrically connect the substrate or the surface layer thereof to a negative electrode of the power supply such that the substrate or the surface layer thereof becomes the cathode, because until now the substrate or the entire surface layer thereof has been made of metal.
However, when forming a metal film on a surface Da of a conductor pattern layer D formed on a surface Ba of a resin substrate B, as shown in FIG. 10A, the conductor pattern layer D must be electrically connected to the negative electrode of the power supply so that the conductor pattern layer D becomes the cathode.
Therefore, for example, an extension portion DL in which a portion of the conductor pattern layer D extends to a peripheral edge portion Bc of the resin substrate B is provided, as shown in FIG. 10B. This extension portion DL is made to contact a metal base 40 that is electrically connected to the negative electrode of the power supply, and a metal film is formed on the surface of the conductor pattern layer D. After the film is formed, the extension portion DL is an unnecessary conductor pattern layer, so this extension portion DL must be removed from the resin substrate B.